1(a) Field of the Invention
The present invention relates to an improved device for measuring the amount of air-borne particles (i.e. fume) that may be inhaled by a workman (especially a welder).
1(b) Brief Description of the Prior Art
As evidenced by U.S. Pat. Nos. 4,178,794; 4,350,507 and 4,455,881, there presently exist various types of devices to be worn by a workman for measuring the amount of air-borne particles in a given area of work.
More particularly, U.S. Pat. No. 4,178,794 describes a device intended to be worn on a workman's chest. This device comprises a cassette provided with an inlet, an outlet and an air filter, the inlet of the cassette being connected to a cyclone which separates respirable and non-respirable air-borne particles, while the outlet of said cassette is connected to a portable vacuum pump.
U.S. Pat. No. 4,350,507 describes a device intended to be suspended either in front of a worker by use of straps passing around his neck and waist, or as an integral part of a helmet worn by said workman. This device comprises a housing defining an air passageway, an electric fan mounted in the passageway, a main filter located across the passageway to collect respirable air-borne particles and a prefilter located across the passageway upstream of the main filter, to collect non respirable air-borne particles.
U.S. Pat. No. 4,455,881 describes a device intended to be worn by a workman for sampling respirable aerosols contained in an atmosphere. This device comprises a selector capillary tube open at one end thereof to the atmosphere, a sampling capillary tube in fluid communication with the other end of the selector tube, and aspiration means in fluid communication with the sampling tube. The capillary tube may be wound on a small spool so that the entire sampling unit is rosette or button sized and can easily be worn by a workman on the lapel or in the manner of a badge.
All of these prior art devices are designed to allow measurements of air-borne particles that may be inhaled by a workman. Unfortunately, they are rather expensive and sophisticated. In addition, they fail to provide means for positioning the air intake within the breathing zone of the workman (i.e. at few centimeters of the workman's nose and mouth area). Also, when the air intake of the device is positioned inside a mask (e.g. in a welder's mask), the corresponding part of the device is fixed to said mask or makes an integral part of it. Therefore, reliable measurements are possible only when the workman wears his mask close to his face.